Incendiary material



Patented Oct. 26, 1948 INCENDIARY MATERIAL David L. Woodberry, United States Army,William W. Howerton, Bel Air, Md., and Alvei- Dunbar, Teaneck, N. J., assignors to the Secretary of War of the United States of America successors in office, as trustee 1..

and his No Drawing. Application November 23,1942,

Serial No. 466,658

(Granted under the act of March 3, 1883, as v Claims.

amended April 30, 1928; 370 O. G. 757) 1 The invention described herein may be manufactured and used b or for the Government for governmental purposes, without the payment to us of any royalty thereon.

This invention relates to improved incendiary.

compositions for incendiary bombs and munitions, such compositions being of a modified thermit type.

The recent widespread and large scale use of incendiary bombs and munitions in War has made the choice of the incendiary compositions to be used for such munitions and bombs a problem of great importance. Because of the great danger, distance, expense, and detailed planning, to

which a tactical unit of the armed services must,;,

go to drop incendiary bombs on enemy installations and military objectives, and because of the momentous effect that a successful bombing mission may have, it is essential that the incendiary bombs used be as effective as possible. other hand, because of the enormous quantities and the extent in and to which such incendiary bombs are used, the amounts of strategic materials required for making such munitions must be kept to a minimum which is consistent With the;,

most efficient functioning and operation thereof.

Accordingly, the object of this invention, generally stated, is the provision of incendiary compositions which operate with the highest degree strategic materials and metals employed therein.

More specifically, the object of this invention is the provision of incendiary compositions for incendiary bombs which compositions have the following improved characteristics in comparison,

On the.

Other objects of th invention-will, in part,--be

obvious and will in part appear hereinaften.

For a more complete understanding of the nature andscope of the invention, reference. may be had to the following detailed-description thereof setting forth,,by wayof illustration, certain specific compositions and methods of compounding the same.

As indicated above,-the invention concerns the provision of modified. -,th ermit compositions which are particularly adapted and suitable as fillings for incendiary bombs and munitions. As is well known, thermit consists essentially of a mixtureofaluminum and iron oxide, which on ignitioniathigh temperature, reacts according to the following, well known, strongly exothermic reaction: k 1

in has been found "that this basic"therm it reaction can be intensified and adapted for incendiary purposes by adding certain ingredients of destructive efiect and utilize to a maximum theff and fine aluminum.

to the standard mix. "One of the essential ingreclients which; should be added is barium nitrate, this ingredient serving primarily to intensify and speed up the thermit reaction. The addition of this ingredient also insures the positive ignition of the incendiary composition and the propagation' of the reaction to completion. However, the barium nitrate cannotbe used to the most advantage as an ingredient by itself, because, among other factors, of its tendency to decompose with explosive violence.

According to this invention, it has been found that themaximum efiect of barium nitrate can be obtained by incorporating therewith additional aluminium of a sufficient degree of fineness so that it reacts with and prevents ,the decomposition of. the barium nitrate with explcsiveviocendiary' compositionsare provided when an oil,

or an oil and sulphur, are incorporated in relatively small quantities with the barium nitrate The following specificexamples of'ince ndiary compositions, forming difierent embodiments of the invention will more completely illustrate and make known to those skilled in the art the nature thereof:

The above composition has been compounded I according to several diiferent procedures. According to one method, which has been found suitable, the proper proportions of aluminum, both granular and grained, and oastor oil are mixed in a suitable mixer until the aluminum is thoroughly coated with the oil. Then, there is added the proper proportions of iron oxide scale and barium nitrate and the mass is mixed until a homogeneous mixture, free from lumps, is formed.

According to a second method of preparation, utilizing commercial thermit, onequarter of the total quantity of thermit, and all of the castor oil are placed in a cone blender with a suitable number of brass balls and mixed for about five minutes. The brass balls are then screened out and the mix is replaced into' the blender.

the mass is mixed for about fifteen minutes.

Example 2 Ingredients percent by weight Iron oxide scale 61.2 Aluminum, granular 19.2 Aluminum, grained 2.8 Aluminum, flaked 1.0 Barium nitrate, free flowing 14.6 Sulphur 0.9 Castor oil 0.3

Example 3 Ingredients percent by weight Hammer scale 60.8 Aluminum, granulan 19.2 Aluminum, grained 2.8 Aluminum, fiakecL, 1,0 Barium nitrate, free flowing 15.0 Sulphur 0.9 Castor oil 0.3

Example 4 Ingredients percent by weight Iron oxide scale -4-.. 59.2 Aluminum, granular 20.8 Aluminum, grained 3.8 Barium nitrate 15.0 Sulphur 0.9 Oil, S. A. E. 30 0.3

The purity, particle sizes, and sources, of the various ingredients used in the above compositions are of importance. The iron oxide material used in the compositions may come from several different commercial sources, such as hammer scale or forge scale, magnetite of suitable purity, and other sources. One type of iron oxide scale which was found to be satisfactory for the compositions of this invention was one meeting the following specifications:

Percent Metallic iron Maximum 1 Ferrous oxide (FeO) Maximum 22 Total iron Maximum 69 Moisture Maximum 0.2

This iron oxide scale had a particle size meeting the following U, S. Standard sieve requirements:

Percent Retained on No. 12 sieve None Passing No. 12, retained on No.

20 sieve Maximum 5 Passing No. 20, retained on No.

50 sieve Minimum 30 Passing No. 140 sieve Maximum 10 The granular aluminum referred to in the above specific examples may be made by stirring molten aluminum slowly while it is cooling and solidifying. As the stirring continues, the aluminum breaks up into flne grains since it is hot short (brittle) at temperatures slightly below its melting point. The particles are rough, irregularly shaped and coarse. The granular aluminum should contain a minimum of 92.5% metallic aluminum and such impurities as copper, iron, silicon, zinc, manganese, lead, and moisture must be controlled within certain limits. The particle size of the granular aluminum used in Examples 1 through 4 was equivalent to the following U. S. Standard sieve requirements:

Percent by weight Retained on No. 12 sieve None Passing No. 12 sieve, retained on No.

30 sieve 13 to 26 Passing N0. 30 sieve, retained on No.

50 sieve 35 to 45 Passing No. 50 sieve, retained on No.

140 sieve 30 to 46 Passing No. 140 sieve 0.0 to 3 The grained and flaked aluminum in the four examples given above were used to react with and prevent the decomposition of the barium nitrate with explosive violence, As will be noted, in Examples 1 and 4 only fine grained aluminum is used, while in Examples 2 and 3 both the flaked and the grained varieties are used.

Grained aluminum may be made by blowing a blast of air against a falling stream of molten aluminum so as to sub-divide the molten aluminum into minute droplets or globules, which, upon solidification, assume a generally nodular form. The grained aluminum should preferably be at least 96% pure and not contain more than 0.2% grease and fat. The grained aluminum used in Examples 1 through 4 had a particle size meeting the following U. S. Standard sieve requirements:

Percent Passing No. 100 sieve Minimum 99 Passing No. 200 sieve Minimum The flaked variety of aluminum may be made by hammering or stamping annealed aluminum sheets or aluminum foil into flakes. A lubricant is added to prevent the flakes from being welded together by the stampin operation. As the stamping or hammering proceeds, the cold working of the'hot metal hardens the foil or sheets so that they readily break into small flakes con- Percent Passing No. sieve Minimum 98 Passing No. 100 sieve Minimum '70 Passing No. 200 sieve Minimum 35 The barium nitrate should beof a high grade, free flowing, variety and have a purity of about 99%. One grade of barium nitrate which served satisfactorily was one having substantially the following U. S. Standard sieve requirements as to particle size:

Percent Passing No. 50 sieve Minimum 100 Passing No. 200 sieve Maximum '75 The sulphur used should be of a high purity grade, a good grade of flowers of sulphur being suitable. The castor oil or other oil used should have a viscosity substantially equivalent to S. A. E. No. 30. As will be noted from Example 1, oil alone may in certain instances be used without the invclusion of sulphur.

It will be understood from the nature of the compositions concerned, the effects and action to be attributed to the different ingredients and grades thereof, cannot in all instances be determined and assigned with accuracy. However, it has been found that incendiary mixtures having the above general compositions function very satisfactorily and fulfill the objects and have the advantages pointed out above.

The incendiary compositions of this invention are adapted to be used as the main incendiary material in incendiary bombs having aluminum, iron, plastic, or other types of bodies. The compositions may also be used as the ignition mixture for magnesium bombs, and as a component of certain oil bombs."

Since certain changes and modifications may be made in theforegoing incendiary compositions and methods of preparing the same,.without departing from the scope of the invention, it is intended that all matter contained in the above description shall be considered as illustrative and that the claims be given a construction as broad as is consistent with the state of the prior art.

We claim:

1. An incendiary composition composed essentially of a uniform mixture of from about 54.7 to about 61.2 parts by weight of iron oxide scale having a particle size substantially equivalent to the following U. S. Standard sieve requirements:

Per cent Retained on No. 12 sieve None Passing No. 12, retained on No. 20 sieve Max. 5

Passing No. 20, retained on No.50 sieve Min. Passing No. 140 sieve Max. 10

Per cent Passing No. 50 sieve 1; MinfIOO Passing No. 200 sieve Max. '75 and from about 23.0 to about 26.0 parts by weight of aluminum, from about 3.8 to about 5.5 parts by weight of said aluminum being sufficiently subdivided that itreacts with and prevents the decomposition of said barium nitrate with explosive violence, and the, remainder of saidaluminum having a particle size substantially equivalent to the followin U. S. Standard sieve requirements:

. Per cent Retained on No. 12 sieve None PassingNo. 12 sieve, retained ,on No 30 sieve ,13 to 26 Passing No. 30. sieve,v retained on No.50

sieve 3 5 to 45 Passing No. 50 sieve, retained on No. 140

sieve 30 to 46 Passing No. 140'sieVe 0.0 to 3 2. An incendiary composition composed e sentially of a uniform mixture of about 55.2 parts by weight of iron oxide scale having a particle size substantially equivalent to thefollowingU. S. Standard sieve requirements:

, Per cent Retained on No. 12 sieve None Passing No. 12, retained on No, 20 sieve" Max. .5 Passing No. 20, retained on No. 50 sieve Min. '30

Passing No. 140 sieve Max. 10

about 19.5 parts by weight of barium nitrate having a particle size substantially equivalent to the following U. S. Standard sieve requirements:

, Percent Passing No. 50 sieve Min. Passing No. 200 sieve Max. 75

about 5.0 parts by weight of grained aluminum having a particle size substantially equivalent to the following U. S, Standard sieve requirements:

- V Per cent Passing No. 100 sieve Min. 99 Passing No. 200 sieve Min. 75

v Per cent Retained on No. 12 sieves... None Passing No. 12 sieve, retained on No. 30

sieve 13 to 26 Passing No. 30 sieve, retained'on No, 50. i

sieve '35 to 49 Passing No. 50 sieve, retained on No.

, sieve 30 to46 Passin No. 140 sieve 0.0 to 3 .and about 0.3 of a part by weight of castor oil.

about 15.0 parts by weight of barium nitrate having a particle size substantially equivalent to the following U. S. Standard sieve requirements:

Per cent Passing No. 50 sieve Min. 100 Passing No. 200 sieve Max. 75

'7 about-3.8 parts by weight of grained aluminum having a particle size substantially equivalent to the following U. S. Standard sieve requirements:

. Per cent Passing No. 100 sieve Min. 99 Passing No. 200 sieve Min. '75

about 20.8 parts by weight of granular aluminum havin a particle size susbtantially equivalent to the following U. S. Standard sieve requirements:

, v Per cent Retained on No. 12 sieve None Passing No. 12 sieve, retained on No. 30

sieve 13 to 26 Passing No, 30 sieve, retained on No. 50

sieve 35 to 49 Passing No. 50 sieve, retained on No. 140

sieve 30 to 46 Passing No. 140 sieve 0.0 to 3 Percent Retained on No. 12 sieve None Passing No. 12, retained on No. 20 sieve.. Max. 5 Passing No. 20, retained on No. 50 sieve Min. 30 Passing No. 140 sieve Max.

about 14.6 parts by weight of barium nitrate having a particle size substantially equivalent to the following U. S. Standard sieve requirements;

, Percent Passing No. 50 sieve Min. 100 Passing No. 200 sieve Max. 75

about 1.0 part by weight of flaked aluminum having a particle size substantially equivalent to the following U. S. Standard sieve requirements:

. Percent Passin No. sieve Min. 98 Passing No. 100 sieve Min. 70 Passin No. 200 sieve Min. 35

about 2.8 parts by weight of grained aluminum having a particle size substantially equivalent to the following U. S. Standard sieve requirements:

Percent Passing No. 100 sieve Min. 99 Passing No. 200 sieve Min. 75

, about 19.2 parts by weight of granular aluminum having a particle size substantially equivalent to the fOllOWing U. S. Standard sieve requirements:

Percent Retained on No. 12 sieve None Passing No. 12 sieve, retained on No. 30

sieve -s 13 to 26 Passing No. 30 sieve, retained on No. 50

sieve 35 to 49 Passing No. 50 sieve, retained on No. 140

sieve 30 to 46 Passing No. 140 sieve 0.0 to 3 about 0.9 of a part by weight of sulphur, and.

about 0.3 of a part by weight of castor oil.

8 5. An incendiary composition composed essentially of a uniform mixture of about 60.8 parts by weight of hammer scale having a particle size substantially equivalent to the following .U. S. Standard sieve requirements:

Percent Retained on No. 12 sieve None Passing No. 12, retained on No. 20 sieve.- Max. 5 Passing No. 20, retained on No. 50 sieve Min. 30 Passing No. 140 sieve Max. 10

about 15.0 parts by weight of barium nitratehaving a particle size substantially equivalent to the following U. S. Standard sieve requirements:

Percent Passing No. 50 sieve Min. 100 Passing No.200 sieve Max.

about 1.0 part by weight of flaked aluminum having a particle size substantially equivalent to the following U. S. Standard sieve requirements:

- Percent Passing No. 20 sieve Min. 98 Passing No. 100 sieve Min. 70 Passing No. 200 sieve Min. 35

about 2.8 parts by weight of grained aluminum having a particle size substantially equivalent to the following U. S. Standard sieve requirements:

' Percent Passing No. 100 sieve Min. 99 Passing No. 200 sieve Min. 75

about 19.2 parts by weight of granular aluminum havin a particle size substantially equivalent to the following U. S. Standard sieve requirements:

Percent Retained on No. 12 sieve None Passing No. 12 sieve, retained on No. 30

sieve 13 to 26 Passing No. 30 sieve, retained on No. 50

sieve 35 to 49 Passing No. 50 sieve, retained on No.

sieve r- 30 to 46 Passing N0. 140 sieve 0.0 to 3 about 0.9 of a part by weight of sulphur, and 0.3 of a part by weight of castor oil.

DAVID L. WOODBERRY.

WILLIAM W. HOWERTON.

ALVER DUNBAR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Hammond Nov. 21, 1922 Number FOREIGN PATENTS Country Date Great Britain 1919 Great Britain June 13, 1938 Number OTHER REFERENCES Zanetti, Fire from the Air, Columbia Univer-/ sity Press (1942), page 11. 

